Hydraulic machine circuit



Feb. 2-, 1943. w. ERNST 2,309,758

HYDRAULIC MACHINE CIRCUIT Filed May 5', 19:59 a Sheet s-Sheet 1 H1. m, ml I 3 Sheets-Sheet 2 @QQQQQQQQ w. ERNST HYDRAULIC MACHINE CIRCUIT Filed ma 5; 1939 Jun-m WALTER ERNT,

Feb. 2, 1943.

7 w. ERNST HYDRAULIC MACHINE CIRCUIT Feb. 2, 1943.

Filed May 5. 1959 3 Sheets-Sheet 3 am 6, M 4W. 1 M 5 l 8 5 5 5 1 m w s 7 M 5 5 w m. m n W m w 0 l 6 W 6 8 5 3 I 3 I T B 7/ w// A/ I 7 M w 6 I I! y g Jmlm WALTER ERNST} Patented Feb.,2,1943

nrnnauuo momma: cmourr Walter Ernst, Mount Gilead, Ohio, assignor to The Hydraulic Development Corp. Ina, Wilmingto'n, DeL, a corporation of Delaware Application May 5, 1939, Serial No. 212,011,

4 Claims.

This invention relates to hydraulic machinery,

and in particular, to hydraulic press systems.

One object of this invention is to provide a hydraulic press system having a hollow main ram with a booster area in a booster .chamber, and an adjustable booster ram therein, arranged initially subsequently to automatically supply pressure fluid tothe main ram area after themain ram.

has traveled a predetermined variable distance, dependent upon the adjustment of the booster rain.

Another object is to provide a hydraulicpress system having a main ram with a mainram area and a booster area within the main ram, and a fluid passageway interconnecting the main ram area with the booster area, the pressure fluid being conveyed tothe booster area by means of a fixed booster plunger having a bore thereth-rough, the head of the fixed plunger being adapted to uncover one end of the passageway after the main ram has moved a predetermined distance so that the pressure fluid flows into the booster ram chamber and then through the passageway to the main ram chamber so as to apply the full force of the pressure fluid to the'entire area of 3 the main ram.

Another object is to provide a hydraulic press system or the type set forth in the preceding objects wherein a single pressure fluid connection ing a check valve chamber connected to an un-- loading valve chamber within which an unload,- ing valve plunger reciprocates, this plunger havin a plunger lifting chamber which is connectible to a source 01' pressure fluid so that the ball check valve portion permits flow of fluid in but one direction, yet the unloading plunger when operated by pressure fluid within its pilot chamher permits flow of-fluid in the'opposite direction wherein the ball check valveis closed.

Another object is to provide a hydraulic press system having a ram within 'a cylinder, together with a by-pass-pas'sageway interconnecting the cylinder bore portions on opposite sides of the v to supply pressure fluid to the booster area and piston head of the ram, thispassageway having a i Q plurality of spaced ports so as to cause by-passing oi the fluid and halting of the plunger at one 01' a plurality of predetermined positions.

In the drawings:

Figure l is a diagrammatic view, partly in section, showing the hydraulic press system of this invention in a preferred embodiment. Figure 2 is a fragmentary view of a portion of Figure 1 showing the main ram in its. advanced position.

v Figure 3 is a central vertical section through the combination check and unloading valve of -the invention.

Figure 4 is a central vertical section through a modification of the invention, showing the in- .vention applied toa vertical typeof press.

Figure 5 is an. enlarged view of a: portion of Figure -1, showing the multiple by-pass ports and check valves associated with them.

In general, the hydraulic press system of this invention consists of a main cylinder having a main ram area and main chamber connected to a combination check and unloading valve, which, in tum,'communicate with a fluid reservoir, suchas an oil tank. The-main ram is hollow, being provided with a central chamber into which a stationary piston -projects. This stationary piston is hollow and at its outer endis connected to a source or pressure fluid through suitable control valves." The main ram is provided with one or more internal passageways opening into the chamber within the main ram through ports, which are arranged to be uncovered as the main ram travels relatively to the head of the station ary hollow piston. In this manner pressure fluid is first conveyed through the hollow piston to the central or booster chamber of the main ram and after the latter has traveled a predetermined distance this fluid also reaches the main ram area through the passageways.

The combination check and unloading valve connected to the main ram chamber consists of a single casing having two chambers, namely a check valve chamber and an unloading valve chamber. A ball member is free to move to and fro within the check valve chamber, whereas a spring urged plunger reciprocates in the unloading valve chamber. Above the unloading valve chamber is a separate plunger lifting chamber to which pressure fluid may be admitted to cause the unloading valve plunger to lift, thereby open-'- ing communication from the check valve chamber through the unloading valve chamber to a discates.

charge conduit. This discharge conduit may lead to the fluid reservoir such as an oil tank.

Referring to the drawings in detail. Figure 1 shows diagrammatically the hydraulic system of the invention as applied to a plastic injection molding press. The press, generally designated to thedie cavity within the mold or die mounted upon the die head 46.

The die head is relatively stationary but is capable of a limited'amount of motion for cushioning purposes. For this reason the die head 46 is mounted upon a plurality of cushioning pis- III, is supplied with pressure fluid from a pair of ,pumps H and I2 driven by a motor ii. The distribution of the pressure fluid from the pumps i i and i2 is regulated by a pair of four way valves l4 and i5, these valves being arranged to be shifted either by the operator or by automatic means. The details of the construction of these pumps and valves form no part of the present invention. Also associated with the circuit is a combination check and unloading valve l6. A pair of safety valves I1 and I8 serve to release pressure fluid inthe event of the failure of other safety devices.

The pumps H and 12 are preferably of the varimembers to neutral positions when the pressure in a part of the circuit reaches a predetermined maximum. The safety valves I1 and I8 protect the circuit against overpressures inthe. event that this so-called pump centering mechanism fails to operate.

The plastic injection molding press to which the invention is applied is shown at the top of Figure 1 and consists of a clamping unit l9, a die cushioning unit 26, and an injection unit 2|. The supporting structures, such as the machine frame, are omitted in order to simplify the showing and illustrate theremaining details more clearly.

The injection unit 2| consists of a cylinder 22 within which a double-acting piston 28 recipro- Connected to the piston 28 is a piston rod 24 which for purposes of simplification is shown to constitute an injection plunger which reciprocates in the material injecting chamber 25. The latter has a bore 26 and a nozzle 21, together with a hopper 28 having a passageway 29 communicating with the bore 26. The piston rod 24 is surrounded by a packing 38 adapted to be compressed by a gland 8| in order to prevent leakage. The opposite ends of the cylinder 22 are provided with ports 82 and 83 connected by the conduits 84 and 85 to the injection control valve l4. The latter is provided with an exhaust conduit 86 leading to the oil tank 81, and likewise with a pressure fluid inlet conduit 98 connected to the pump'l If. The pump II is provided with a-suction conduit 89 opening into the oil tank 81. The safety valve I1 is connected by the conduit 46 to the conduit 88 and discharges through the conduit 4i into the tank 81. The injection cylinder 22 is provided with a pair of additional ports 42 and 49 interconnected by the conduit 44 containing the ball check valve 45. This arrangement serves to halt the retraction of the pisten 28 when it passes the port 48 at its rear edge, therebyserving to bypath the discharge of the Dump through the line 44 and check valve 45.

The cushioning unit consists of a substantially stationary die head 46 upon which one of the molding dies is mounted (not shown). The die head 46 is provided with a socket 41 for receivin the nozzle 21. The socket 41 communicates with a material conveying passageway 48 which, leads the main ram 68.

tons 49 (one only being shown), these reciproeating in die cushioning cylinders 88. The piston 49 is connected tothe die head 46 by means of a piston rod SI, and a tail rod 62 extends in the opposite direction from the piston 49. The plston rod 5| and tail rod 62 are provided with longitudinal passageways 5i and 64 leading respectively to conduits 55 and 66. These conduits are connected as described below.

The die clamping unit i9 consists of a cylinder 51 within which the main ram 68 reciprocates. On the end of the main ramll is mounted a platen 69 serving to support and move the movable die or mold (not shown) which cooperates with the stationary die or mold mounted upon the die head 46. The main ram 68 is provided with a head 60 and a piston rod 6| connecting the head 60 with the platen 69. Leakage around the piston rod 6i is prevented by a gland 62 and spaced packings 63 and 64 separated by a chamber 65. From the latterthe port 66 is connected to the drainage conduit 61 leading downward to the tank 81.

The piston rod 6| is provided with an internal bore 68, the end 69 of which forms the so-called booster area of the main ram 68. Opening into th bore 68 are ports 10 having passageways H to the main ram area 12 on the end of the piston head 60, the opposite end 18 or which forms the retraction area. On the opposite side of the main ram piston head 60, when the latter is in its retracted position, are spaced ports I4 and I6 interconnected bya bypath passageway 18.

Near its forward end the cylinder 61 is provided with a port 11 connected to a conduit 18 leading to the four way clamping control valve IS. The latter is served by a conduit 82 connecting it with the pump l2 so as to receive a supply of pressure fluid. Also connected to the valve II is an exhaust conduit 19 discharging into the oil tank 81. A port conduit leads from the clamping control valve to the port 8| at the rearward end of the main cylinder 61 by way of the connection can 82. The port 8! leads into a passageway or chamber. 88 surrounding the piston rod 84. The chamber 88 is closed by an end plat 85. The piston rod 84 carries a piston head 86 fitting smoothly into the bore 68 within Piston rod 84 and piston head 86 are traversed by an L shaped passageway 81 leading from the chamber 88 to the bore 88 adjacent the booster area 69. The piston-rod' and piston 86 are held in a stationary position by means of the threaded portion 88 threaded into the threaded bore 89 in the cylinder 61. It will be observed that the conduits 68 and 66 leading from the opposite ends of the piston rod 6i and tail rod 52 associated with the cushioning unit 28 are connected respectively to the conduits 88 and 18 leading to the opposite ends of-the main cylinder 61. The rearward end of the main cylinder 51 is provided with a port 99 to which is con- .nected the conduit 9| leading to the combination ty valve i8 withan intake conduit 96 connected to the conduit 92, together with an exhaust conduit 90 which discharges into the tank 31.

The combination check and unloading valve I5 (Figure 3) consists of a casing 91 having a chamber 99 for receiving a ball check'valve member 99 which is engageable with an annular seat I in the form of a sleeve coaxial with the chamber 98. The latter is provided with guide ribs IOI along its innerwalls and serving to guide the ball 99 in its up and down motion, limited also by the rod I02. The conduit -9I opens into a threaded port I03 at the top of the chamber 98 whereas the conduit 92 opens into a port I04 at the bottom thereof beneath the ball 99. A side port I leads into an adjacent unloading valve chamber I00 communicating with a vertical bore I01 within which the unloading valve plunger I08 reciprocates. Above the upper end of the bore I01 there is provided an enlarged coaxial bore I09 shown in Figure 2, this pressure immediately closes the ball check valve member 99 upon'itsserving to receive the pilot head IIO on the valve plunger I00. The latter is surrounded by the annular plunger lifting chamber III having a threaded port' i I2 to which is connected the conduit H3 leading to a connection with the conduit 18, andthereby connected to the retraction circuit for the main ram 59. Above the enlarged head IIO the plunger I08 is providedwith a further enlargement I I4 reciprocable within a spring chamber II5 closed by a cap IIB secured to the casing 91 by the screws II1. Beyond the enlargement II4 the plunger I08 is provided with a reduced diameter portion H8 surrounded by a spring 9 urging the unloading valve plunger I08 downwardly to a'position closing the bore I01 leading into the pipe 99. Consequently when pressure fluid is admitted into the pipe m and then into the plunger lifting chamber III the valve plunger I08 rises and opens the port I 05 into communication with the conduit 93.

Operation ,be in the retracted positions shown in Figure 1, the operator now operates theclamping controlvalve I5 and ,the injection control valve I4 to operate the press I0 in its various movements.

- To clamp the dies, the operator shifts the valve member I20 of the clamping control valve upwardly, thereby placing the pressure conduit 92 in communication with the conduit 90. Pressure fluid then flows from the pump 12' through the conduits 82 and 80 to the port 8!, thence into the chamber 83 and through the piston rod passageway 91 into the end of the ram chamber 59 adjacent the booster area 69 thereof. As the latter area is of relatively small diameter, the main ram 58 and platen 59 move forward at a relatively rapid rate. Meanwhile, the fluid in front of the ram head'60 is discharged through the port 11, the conduit 18, the valve I5 and the exhaust con- .duit 19 into the oil tank 31.v

When the main ram 59 has traveled forward to a point where the ports 10 are uncovered in passing the stationary piston head 89 (Figure 2) the pressure fluid within the boosterchamber 99 escapesthrough the ports 10 and passageways 1| into the rearward end of the main cylinder 51 to the left of the main ram area 12. The full through the conduit 55 into the cushioning cylinder 50 and thereby yieldingly supports the die head 49 and the die or mold half carried thereby. The fluid on the opposite side of the pis- 5 ton head 49 escapes through the conduit 56 to I of the pump I2 automatically shifts to its neutral position. Meanwhile, as the mainram 58 has advanced, fluid isdrawn into the rearward end of the main cylinder 51 through the pipe 9I and past the ball check valve member 99,, 15 which is raised by the suction thus created. In

this manner, fluid passes upwardly from the oil tank 31 through the pipes 92 and 9I to the main cylinder 51. When pressure enters the rearward end of the main cylinder 51, however, as

seat I00, aided by gravity.

To perform an injection stroke after having placed injection molding material in the hopper 29 and suitably heated the injection cylinder 25, the dperator shifts the valve member I2I of the. injection control valve I4 upwardly, thereby admitting pressure fluid from the pump discharge line 38 to the conduit 34 and thence into the right hand end of the injection operating cylinder 22. This pressure acts against the piston head 23 and pushes it and the piston rod 24,-

together with the injection molding material through the bore 26 and out the nozzle 21 into the channel or passageway 48 whence it passes into the mold cavity between the mold halves.

To retract the injector, the operator moves the valve member I2I downward aided by the coil spring I22 so that the flow of pressure fluid to 40 the. injector piston H3 is reversed, pressure fluid entering through the conduit 35 and the displaced fluid returning to the tank through the conduit 34 and the exhaust conduit 36. When the piston head 23 passes the port 43 in the 45 cylinder 22, fluid then flows through the conduit and past the check valve 45 into the right hand end of the cylinder 22, then through the conduits 34 and 39 into thetank 31, thenceforth by-passing the discharge of the pump II and halting the retraction of the piston head 23.

To unclamp the dies or mold halves, the operator moves the valve member I20 of the clamping control valve I5 downwardly aided by the coil spring I22. Pressure fluid is now supplied by I the pump I2 through the line 18 and port 11 to the retraction side 13 of the main ram head 00 retracting the main ram 59 from its Figure 2 position to its Figure 1 position.' At the same ure 3) and through the chamber I06, into the exhaust-conduit 93. When the piston head 60 arrives at the positionshown in Figure 1,'it uncovers. the port 15, whereupon the fluid is bypassed around the piston head 60,'h alting the further travel thereof.v At the same time, the clamping plunger 49 moves backward and ends 15 its'cushioning action. The foregoing cycle of to be varied as the main ram 58 advances.

operation can then 'be.repeated in the same manner.

The piston rod 04 is provided with suitable or retract the head 86 longitudinally. This arrangement, by reason of the threaded mounting of the threaded portion 88 in the threaded bore 89 and the annular chamber 83, enables the point at which the head 86 uncovers the portsO Y this arrangement the apparatus can be adjusted accurately to diiferent thicknesses of dies mount- .ed upon the die carriers 46 and 59.

The modified form of press shown in Figure 4 utilizes the invention in a vertical type of press.

The construction of the ram and its associated mechanism is substantially the same as that shown in Figures 1 and 2, and similar parts bear the same reference numerals. Mounted above the main cylinder 51, however, is a surge tank I 3I for containing the working fluid, such as oil. The main cylinder 51 is also provided with a bore I32 containing a surge valve I 33 of a conventional type, such as that shown in the patent to Ernst 'No. 1,892,568, issued December 27, 1932, the details of which form no part of the present invention. This surge valve opens during the initial advance of the main ram, and serves to prefill the main cylinder 51 during the first part of the stroke'of the main ram. When pressure builds up above the main ram, however, the surge valve I33 automatically closes and permits the completion of the working stroke.

In Figure 4 the conduits 80 and I8, instead of being connected to afour-way valve as 'in the open circuit of Figure 1, are shown as connected to the ports of a reversible variable delivery pump I34 having a servomotor I34 with a servomotor control valve member I35, by which the pump I34 may be caused'to deliver pressure fluid either through the conduit 80 or through the conduit I8, as desired. Running from the conduit I8 is a branch conduit I36 leading to the operating chamber of the surge valve I33, and also leading to the check valve I31 within the surge tank I3I. The operation of the modification shown in Figure 4 follows the same principles as the circuit shown in Figure 1, with the exception of the fact that the delivery of the pump I33 is reversed in order to retract the main ram. The hollow piston rod 84 and piston 86 are adjusted by inserting a wrench in the wrench socket I38, having a similar purpose to the squared end I30 in Figure 1. The annular chamber. surrounding the piston rod 84 is also contained in a separate casing I39, secured by the bolts I40 to the main cylinder 51.

The construction shown in Figure 5, and on a smaller scale in Figure 1, is for the purpose of causing the halting of the piston head 60 at different points on its retraction stroke. A pres of this type frequently employs dies of diflerent thicknesses, depending upon the kind'o'f workpiece to be molded, It is necessary, in designing such a press, to provide for a suflicient retraction of the main ram 58 to enable the use of the thickest dies likely to be encountered in ordinary practice. When thin dies are used, such as for the making of thin work-pieces, valuable time is lost in retracting the main or clamping plunger 58 to a greater distance than is necessary for opening the dies and ejecting the work-piece. The arrangement shown in Figures 1 and 5 enthin dies the main ram or clamping ram 58 will be retracted a shorter distance than with thick dies. Such thin dies are used, for example, in the making of combs or spectacle frames.

In addition to the by-pass ports I4 and IS, the by-pass passageway I6 is provided with additional ports I 4| and I42 on the retraction side of the main ram head 80. These ports I M and I42 are provided with valve seats I43 and I 44, containing ball check valves I 45 and I46. Opposite the valve seats I43 and 144 are threaded ports I41 and I48, into which screws I49 and I are threaded. By rotating these screws to bring their inner ends into engagement with the balls I45 and I46, the ports I and I42 may be positively closed so that the ram head will not halt until it uncovers the port 75. If, however, it is desired to halt the ram head at an intermediate port, the screw I49 is rotated in a reverse direction so as to permit the ball I 45 to move. Accordingly, when the ram head 60 uncovers the port MI,

I on its retraction stroke, the ball I45 will be forced tion of the main of clamping ram 58.

If extremely thin dies are to be used, the screw I50 is also rotated to free the ball check valve I 46, Accordingly, when the port I42 is uncovered by the ram head 60, during the retraction stroke, pressure fluid will 'flow through the port I42 into the by-pass passageway I6, after raising the ball check valve I46 away from its seat I44. Thus, the ram head 60 will halt after a shorter retraction stroke than if the port I 4| or the port I5 were employed.

The screws I49 and I50 may either be solid or may be provided with so'ckets I5I, with springs I52 engaging the ball check valves I45 and I46. Caps I 53 are provided for covering the ends of 'the screws I49 and I50 so as to discourage tamables the apparatus to be adjusted so that for I54 may also be optionally provided to lock the screws I49 and I 50 in their adjusted positions. The operation of the by-pass arrangement shown in Figure 5 has been described in connection with its contsruction, and requires no further description.

It will be understood that I desire to comprehend within my invention such modifications as come within the scope of the claims.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is: V

1. In a hydraulic press, a main cylinder body with a cylinder bore and an end chamber spaced therefrom by a threaded portion, means for admitting pressure fluid to said end chamber, a ram reciprocably mounted in said cylinder bore and comprising a booster chamber and a main ram area, aplunger having a threaded portion longer than said threaded bore and being adjustably mounted therein, said plunger having a bore therethrough for continuously establishing hydraulic connection between said end chamber and one end of said booster chamber, means for selectively establishing hydraulic communication between the said end of said booster chamber and said main ram area, means associated with said plunger for substantially preventing the supply of any pressure fluid to said main area prior to the completion of a predetel-mined stroke of said ram, and means operable 'irom the outside of said press for rotating said plunger to vary said'predetermined stroke.

2, In a hydraulic press, a main cylinder having a bore at one end thereof engaging a plunger to permit axial movement therein, a main ram arranged in said cylinder and having a main area and a booster chamber, said cylinder having a port for admitting pressure fluid to said booster chamber to cause a fast traverse movement of i said main rain, a plunger having means thereon engaging said bore for permitting axial movement thereof in said bore, said plunger being provided with a passageway therethrough continuously effecting hydraulic communication be- I tween said port and said booster chamber, conduit means associated with said ram and responsive to a predetermined point of travel of said ram relative to said plunger for conveying fluid pressure from said booster cylinder to said main ram area to subject said ram to an increased pressure, and means operable from the outside of said press for varying said predetermined point of travel.

, 3. In a hydraulic press, a main cylinder having an end chamber and a main chamber with a threaded bore extending from said main chamber into said end chamber, a fluid source adapted to supply pressure fluid to saidend chamber, a

main ram having an outer ram area in said main chamber and a central irmer chamber with an auxiliary inner ram area, a passagewayextendmg from-said main chamber to said inner chem connecting said ports;

to said outer ram area, and means on said sta tionary plunger and operable from the outside of said end chamber for rotating said stationary plunger to selectively effect longitudinal movement of said head in one or the other direction with respect to the opening of said passageway in said inner chamber whereby to vary the point of admission of pressure fluid from said end chamber to said main chamber. 1

4. In a hydraulic press, a main cylinder having an end chamber and a main chamber with a threaded bore extending from said main chamher into said end chamber, a fluid source adapted to supply pressure fluid to said end chamber,

conduit means for connecting said fluid source with said end chamber, a main ram having an outer ram area in said main chamber and a central inner chamber with an auxiliary inner ram area; a passageway extending from said main chamber to said inner chamber at a, location remot from said inner ram area, a. hollow stationary plunger with a threaded portion adjustably engaging and being longer than said threaded bore and with a head engaging said central inner chamber, s-ld stationary plunger havinga bore therethrough leading from said end chamber longitudinally through said plunger and its head into said inner chambenand being adapted at a predetermined point of travel to convey pressure fluid from said end chamber to said pfls'sageway, means connected to said plungerand operable from the outside of said main cylinder to rotate said plunger for selectively moving the same in,

one or the other direction without aifectlng the connection of said conduit means with said end chamber, and means for varying the maximum stroke of said main ram, said main ram having a ram headan'd said main cylinder having a port on each side of said ramhead in the retracted position thereof, and a by-pass conduit inter- I wanna nansr. 

